A steam turbine includes a rotor which rotates about an axis and a casing which covers the rotor. The rotor includes a rotor shaft which extends in an axial direction about an axis and a plurality of stages of rotor blade rows which are fixed to an outer periphery of the rotor shaft and are arranged in the axial direction. The steam turbine includes a stator vane row which is fixed to an inner periphery of the casing and is disposed on an upstream side of each stage of the plurality of stages of rotor blade rows.
A steam turbine of Patent Document 1 includes a ring-shaped protrusion which protrudes from a downstream side end surface of an inner ring provided on an inner peripheral side of a stator vane of a stator vane row toward a downstream side thereof. In addition, the steam turbine includes a ring-shaped protrusion which protrudes from an upstream side end surface of a tubular rotor blade support portion provided on an inner peripheral side of a rotor blade configuring a rotor blade row toward an upstream side thereof. In addition, in the steam turbine, the ring-shaped protrusion on the stator vane side is disposed on the outer peripheral side of the ring-shaped protrusion on the rotor blade side, and the protrusions are provided to overlap each other in an axial direction. Accordingly, a gap between the stator vanes and the rotor blades is bent in a crank shape, and thus, steam flowing through a steam main flow passage is prevented from leaking from a gap between the rotor blade rows and the stator vane rows toward the inner peripheral side.